Giardiasis, 2002

During 2002, 982 cases of Giardia infection (20.0
per 100,000 population) were reported. This represents a 7%
decrease from the 1,061 cases reported in 2001 and is near
the low end of the range of the annual number of cases reported
from 1996 through 2001 (median, 1,149 cases; range, 971 to
1,556).

The median age of case-patients reported in 2002 was 30
years. As in previous years, cases were clustered among children
less than 5 years of age (21%); only 15% of cases were over
50 years of age. This age distribution suggests a higher risk
for transmission among young children and the adults who care
for them. Overall, 6% of case-patients were hospitalized;
17% of case-patients over 50 years of age were hospitalized.
No food-borne or water-borne outbreaks of giardiasis were
reported in 2002.

MDH began systematically interviewing cases of giardiasis
in January 2002 in order to better characterize the illness
and evaluate potential risk factors for infection. Fifty-eight
percent of cases were interviewed. The symptoms most commonly
reported by case-patients included diarrhea (97%), fatigue
(84%), gas or bloating (79%), abdominal pain (77%), and nausea
(61%); less commonly reported symptoms included vomiting (36%)
and chills or fever (27%).

Forty-one percent of interviewed cases reported traveling
in the 10 days prior to their illness onset. Among case-patients
who reported travel, 28% reported travel outside the U.S.
Twenty percent of case-patients reported camping or hiking
in the 10 days prior to illness onset, and 41% reported having
gone swimming or entered water before their onset. Fiftyeight
percent of adult case-patients reported having children in
their households; 59% of those case-patients had children in
diapers. Thirty-eight percent of adults reported changing
a diaper within the 10 days before their onset. Among giardiasis
cases in children, 41% of interviewed parents reported that
their child had contact with a childcare setting in the period
before and/or during illness.